Fix: Remove unused form error-handling; add new placeholder + regex

[machikoyasuda]

closes #1007

What this PR does

• Remove form with-errors related HTML, CSS, JS and Python method
• Add sample placeholder and regex

How to test

• Run ./bin/init.sh to get the new sample data regex/input placeholder
• Go through both forms and ensure no regressions in style and function
• Go through Input form: Test an input that fails the regex

[thekaveman]

I ran through the CC flow for:

1. Input that doesn't match the regex ✅
2. Input that is verified ✅
3. Input that is not verified ✅

It all looks good; maybe we can clean the spacing up later.

[machikoyasuda]

@thekaveman Yea - on spacing, this next PR #1023 would be the best time and place to change the Form template spacing. As far as I can tell, the linters don't do anything for anything in between <script>....</script> on these pages. For now, I'm just making sure the if/elses and open/close elements are all aligned.